The present invention relates to a finder system used in a camera. More specifically the present invention relates to a finder system used in a SLR (single lens reflex) camera which has a display for indicating operating parameters of the camera, such as shutter speed, aperture value etc., and a device for detecting a direction that a person's eye looking through the finder system, is focused on (hereinafter referred to as an eye direction detecting device).
Recently SLR cameras have been provided with a viewfinder display and an eye direction detecting device. The eye direction detecting device consists of a light source used to illuminate the person's eye and a senor to detect light reflected back from the person's eye. The reflected light from the eye is transmitted through an eyepiece lens and a pentaprism. The light then exits the pentaprism and is reflected by a detecting prism attached to one surface of the pentaprism towards the sensor of the eye direction detecting device. The sensor outputs a signal that varies with the direction in which the person is looking. A microprocessor of the camera then determines the direction that the person is looking based on the output signal from the sensor.
Further, the display used to indicate the operating parameters of the camera emits light to a display prism attached to another surface of the pentaprism. The display prism reflects the light and transmits the light to the pentaprism where it is viewed through the eyepiece lens by the person.
However, with this construction, a separate display prism and detecting prism are required for the display and the eye direction detecting device, respectively. This increases the size of the camera and the cost in manufacturing the camera.